The present disclosure is generally directed, in various embodiments, to imaging members. More particularly, the disclosure relates to various embodiments of an imaging member comprising a substrate, an undercoat layer (UCL), a charge generation layer, a charge transport layer, and an optional overcoat layer. The undercoat layer is formed from a single phase UCL formulation comprising an organic titanate, a polymer containing active hydrogen, and an aminosilane.
Most of the undercoat layers (UCL) on the market are particulates with metal oxides dispersed in polymeric matrices. For example, United States Patent Application Publication No. 2004/0202947, the contents of which are incorporated entirely herein by reference, has disclosed that an UCL coating dispersion was prepared by ball milling of titanium dioxide and phenolic resin in 1-butanol and xylene with 1-millimeter diameter sized ZrO2 beads for 5 days. The resulting titanium dioxide dispersion was then filtered with a 20-micrometer pore size nylon cloth. Additional solvent, bisphenol S (4,4′-sulfonyldiphenol), and tetraethoxysilane (TEOS) were then added to the dispersion. An aluminum pipe was dip coated with the coating dispersion, and subsequently cured at 160° C. for 15 minutes, resulting in an undercoat layer (UCL) of 2.5˜5 microns thickness.
However, the preparation of the UCL dispersion is typically a complicated process including milling, and the resulting dispersion sometimes has a pot life issue since metal oxides tend to be precipitate out from the organic polymeric solution. Meanwhile, internal cyclic life associated with the dispersed UCL sometimes is not good enough due to the limitations of electron transport of metal oxides and inhomogeneity of the UCL. Furthermore, thick UCL demanded for long operational life.
As such, new UCL formulations with improved properties such as stability, processing convenience, longer internal cyclic life, and longer pot life etc. are needed. Also needed are imaging members such as photoreceptor that has stable, thick UCL coating; resistance to electrical failure; and PIDC independency on UCL thickness etc., among others.